Add 4-Way Splitter to Tap


  #1  
Old 03-29-12, 05:22 PM
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Add 4-Way Splitter to Tap

I've already purchased a 4 way (5mhz-2.4ghz), passive to 1 splitter, to split my digital cable signal to 2 digital cable boxes, 1 QAM tuner to my Dell notebook and 2 hsi cable modems (1 w a gb port and 1 w digital voice port). The splitter that was previously on there was a 5mhz-1ghz splitter to 1 OUT and 1 TAP. So i'm thinking the best way to set this up is to put the cable modems on the 1 TAP end which supposedly limits the signal loss to 6db and use a new 2 way splitter on the TAP end to connect the cable modems, and then on the OUT, connect the 4 way with the QAM tuner to the notebook on OUT #1 so that it will benefit from limited signal loss and then OUT #2 and #3 connected to the two digital cable boxes with OUT #4 capped. I think it will look something like this:


IN ---- TAP -------------- HSI DOCSIS Cable Modem/Wireless Router (10/100Mb/1Gb)
| | \
| | ----------- Cable modem/Digital Voice/Wireless Printer (10/100Mb and Ethernet/USB)
| |
---- OUT ---- IN ---- OUT#1(passive power) to HAUPPAGE QAM Tuner to Dell Notebook
| |
| |OUT#2 (no passive power) to Digital Set Box #1
| |
| |OUT#3 (no passive power) to Digital Set Box #2
| |
| |OUT#4 (no passive power) to Cap to cover Terminal Not in Use
----

Is there a better way to wire this? Thanks!
 
  #2  
Old 03-30-12, 05:32 AM
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Hi blutarske, and welcome to the forums. I moved your post into its own new thread because the one you responded to was nearly two years old.

Depending on the strength of the incoming signal your plan should work fine. If it doesn't you can try swapping the feeds to the 4-way and 2-way (modem splitter).

Plus, you can always add an amplifier. Make sure the amp has a "return path", and make sure it has an upper-range bandwidth of at least 1GHz.

Calculating dB loss is very simple because it's additive at each port. If, for example, the incoming signal is at +15dB you'll have only the insertion loss at the tap's "out" port (usually -1.5dB). Your two-way splitter to the modems will reduce the signal by another 3.5dB to each port. Each modem will therefore see +15 - 1.5 - 3.5 = +10dB.

Again assuming a +15dB signal to the house: For the other splitter you're starting at +9dB after the tap port (since the tap port is -6dB). The splitter introduces a -7dB loss at each port, so your signal is at +2dB to each of those devices.

If the incoming signal is only +10dB the outputs from the 4-way will be at -3dB, which is borderline.

Cable attenuation loss also comes into play. At 1GHz, 100 feet of RG6 will attenuate the signal by -6dB.

This is why you may need an amp. In this case an 11dB amp will work fine. Too much signal is worse than too little signal because it can damage the devices.
 
 

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